00. Overview. Syscall → utility → shell → script → service

Reprise: operating system goals

(aka u/s/l)

Resources:

E. g.:

Interfaces and tools

Supervisor mode (kernel space) and user mode (user space):

Interface levels:

  1. Kernel: syscalls. Used primarily inside kernel code (∃ klibc, in fact). E. g. clone (in fact, huge amount of u/s/l) or in libc library.

  2. Libc: library calls. Used when programming userspace utilities. E. g. fork or daemon, or exec.

  3. Utilities: programs to perform syscalls, with goodies. E. g. env, xargs

  4. Shell: scripting utilities usage. I/O redirection, process manupulation, programming language.
  5. Services (daemons): task is too complex/too slow for shell scripting; back to programming

Also: daemons

«Flower architecture»

system_architecture_flower_EN.svg

Shell (intro)

If there's time

Interface basecs:

So:

⇒ Command line interface (CLI)

Shell:

Shell commands:

Command line conventions ...

Additional topics to discuss

HSE/ArchitectureOS/00_OverviewShell (последним исправлял пользователь FrBrGeorge 2020-06-20 17:05:30)